Process for manufacturing a rapid hardening portland cement

ABSTRACT

This invention relates to a process for manufacturing a modified rapid hardening portland cement of which a setting time is convenient even at low temperature, which comprises mixing calcium carbonate, sodium carbonate, potassium carbonate and/or magnesium carbonate, or a mixture of said carbonate and sodium sulfate, potassium sulfate, aluminium sulfate and/or magnesium sulfate with a clinker which mainly consists of a calcium haloaluminate having the formula 11CaO.7Al2O3.CaX2, intergrinding the mixture and then mixing finely powdered anhydrite with the ground mixture to manufacture cement in an amount such that the weight ratio of Al2O3/SO3 in the cement is 0.6-1.8.

Au 116 EX United States Patent 1191 Uchikawa et al.

1 PROCESS FOR MANUFACTURING A RAPID HARDENING PORTLAND CEMENT 75] Inventors: Hiroshi Uchikawa; Noboru Kasai,

both of Tokyo, Japan 73] Assignee: Onoda Cement Co., Ltd., Onoda-shi, Yamaguchi, Japan [22] Filed: Nov. 27, 1972 [21] Appl. No.: 309,805

[30] Foreign Application Priority Data 1 June 25, 1974 12/1971 Greening et a1. 106/100 Primary ExaminerJames E. Poer Attorney, Agent, or Firm-Oblon, Fisher, Spivak, Mc- Clelland & Maier 5 7] ABSTRACT This invention relates to a process for manufacturing a modified rapid hardening portland cement of which a setting time is convenient even at low temperature,

which comprises mixin calciu arbonate, sodiu carbonate, potassium carbonate and or aw c zg 5nz tg,,or a mixture oi said l ate an sodlum n I ll s te, otasslum s er which mainly conmagnesiumsulfate with a sists of a calcium halo-aluminate having the formula W intergrinding the mixture and then mixing fine y'powdered mm with the ground mixture to manufacture cement in an amount such that the weight ratio of A1 O /SO in the cement is 0.6-1.8.

15 Claims, 2 Drawing Figures PATENTED JUN 2 5 i974 SHEEI 1 0f 2 Fig.

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Blaine Specific Surface Area PATENTED JUN 2 5 I974 Setting Time (Min) SHEEI 2 0F 2 Fig.2

Blaine Specific Surface Area PROCESS FOR MANUFACTURING A RAPID ARDENING PORTLAND CEMENT This invention relates to a process for manufacturing extremely rapid hardening portland cement from clinker containing, as main minerals, calcium haloaluminate having the formula 1 lCaO Al O 'CaX (hereinafter abridged to C A 'CaX wherein X is a halogen), 3CaO-Si0 solid solution (hereinafter abridged to C 8), 2Ca O-SiO solid solution (hereinafter abridged to C 5) and 2CaO'Fe O 6CaO'2Al O 'Fe O (hereinafter abridged to C AF) ferrous solid solution.

A clinker comprising, as hydraulic minerals, c,,A,-cax, and at least one of C 5. C 8 and C AF, etc. is produced by burning raw mixtures of silicious material, aluminous material, calcareous material and a small amount of halogen compound such as fluorite or calcium chloride. As the clinker contains extremely active hydraulic mineral of C A CaX the hydration of only this clinker powder is too fast to develop consider- 2O able high strength both in initial and later ages. Then it has been discovered that when gn hydrite (or anhydrite gypsum) and/or hemihydrate (or hemihydrate gypsum) or gypsum and one or more of sulfate, nitrate and chloride of potassium, sodium, magnesium. calcium, aluminum, and ammonium(excluding gypsum), sugar, sodium hydrogen carbonate, water soluble phosphate, aliphatic carbonic acid, silicofluoride, sodium 5 silicate, lignin sulfonate, higher alcohol ester of sulfuric acid and alkyl-sulfonate was added to the clinker. setting time of cement thus obtained is retarded considerably and mortar strength of the cement was improved in the early and the later stages than that of the former cement.

| desirably in the early and the later stages but below C, a setting time is extremely slow and does not develop in the early age or does not develop at all in the later ages.

Then, the content of anhydrite and additives in cements which are prepared experimentally under the process for manufacturing as mentioned above is shown in Table I. Table 2-l and Table 2-2 show setting time and compressive strength of mortar of these cements.

Table l Blaine Specific Sample Ratio (WLVQ Surface Area "N5? Clinker Anhydrite Additives of Cement cm' lg I 85.0 l4.0 Hemihydrate 1.0 5480 2 85.0 12.0 Hemihydrate 3.0 5530 3 85.0 l4.0 Anhydrite l.() 54l0 4 85.0 l2.0 Anhydrite 3.0 5600 5 850 I Hemihydrate L0 4400 6 85.0 12.0 Hemihydrate 3.0 5660 7 85.0 l4,0 Anhydrite L0 5370 8 85.0 l2.0 Anhydrite 3.0 5420 9 80.0 l3.0 Lime stone 7.0 5450 I0 82.45 14.55 Lime stone 20 5420 l l Anhydrous 1.0

sodium sulfate I I 850 I 5350 I2 80.6 14.0 Lime stone 4.4 5480 Anhydrous |.0 sodium sulfate Note: Sample cements are prepared in the following way:

No. l-2: Hemihydrate of 5200 cm/g(Blaine) and anhydrite of 8000 cm/g(Blaine) are added to powdered clinker. Nod-4: Anhydrite of H.500 cm'-'/g(Blainc) and anhydrite of 8000 cm'/g(Blaine) are added to powdered clinker. No.5-8: Anhydritc of 8000 cm /g( Blaine) is added to a interground mixture of hemihydrate or anhydrite and clinker. No.9-l0: Anhydrile and lime stone or lime stone and anhydrous sodium sulfate are added to clinker and intergrountl. Nol l-l2: Separately ground anhydrite, lime stone and anhydrous sodium sulfate are mixed.

Table 2-l Test Tem erature 5C Test Tgmpgrature l0C Setting Compressive Strength Setting Compressive Strength Time of Mortar Time of Mortar (Kg/cm'flnitial- Initial- Sample Final 2 3 6 l 3 28 Final 2 3 6 l 3 28 No. (min) hrs hrs hrs day days days (min) hrs hrs hrs day days days l l 204 4l-62 4| 170 256 294 2 2| I95 l330 ll 3 2 2 3 48 l90 49-7l 22 8| M4 202 303 Table 2-1 Continued Test Temperature C Test Temperature C Setting Compressive Strength Setting Compressive Strength Time of Mortar Time of Mortar (Kg/cmflnitial- Initial- Sam le Final 2 3 6 l 3 28 Final 2 3 6 l 3 28 No. (min) hrs hrs hrs day days days (min) hrs hrs hrs day days days 4 220-340 8 70 295 5 56 208 68-97 28 69 186 250 321 6 235-390 44 202 7 77 202 58-70 77 167 210 306 8 191-200 19 120 291 9 181 l l 105 10 6] 226 I4 102 ll 80 250 -59 5 92 180 268 303 12 10 90 309 72 31 202 278 348 Table 2-2 Test Temperature 20C Test Temperature 30C selling Time Compresshe Strength Semng Time Compressive Strength sample initial-final 91" (kg/c1112) I id LFi I of mortar (log/em t No. (min) 2 hrs 3 hrs 1 day 3 days 28 days (min) 2 hrs 3 hrs 1 day 3 days 28 days Note For thc test temperature of 30C. citric acid in the amount of 0.2% by eight of cement was added to all the samples as rctardur.

Table l and 2 showed that a setting time of these cements was convenient and strength of mortars developed considerably both at 20 and 30C, however, at the lower temperatures of 5 and 10C, a setting time was extremely lengthened and early age strength of mortars were low or did not develop and in later ages strength of mortars did not develop sufficiently too. It was further observed that this characteristics was not improved, as shown in the samples No. l-8, by decreasing an amount of hemihydrate or anhydrite added as a retarder or, as shown in samples No. 11, in the absence thereof.

An object of this invention is to provide a process for manufacturing a modified extremely rapid hardening portland cement whose mortar setting time is convenient even at low temperature and its compressive strength in early and later ages develops sufficiently through a wide range of temperature from low to high,

Further and additional objects of this invention will appear from the following description and the appended claims.

In accordance with one embodiment of this invention, a modified portland cement is prepared by the process in which a mixture of a carbonate of calcium, sodium, potassium or magnesium, or a mixture of said carbonate and a sulfate of sodium, potassium, aluminium or magnesium and clinker containing C A 'CaX is interground and then anhydrite powder is added to the resulting mixture powder.

This invention can be more fully understood from the following detailed description when taken in conjunction with reference to the accompanying drawings, in which:

FIG. 1 and FIG. 2 show the relation between fineness of cement prepared by this invention, and a setting time and compressive strength of mortar prepared from the cement.

The results of experiments conducted by using the clinker of the same composition as the above test(C- A -CaF 24 percent, C,,S 49 percent) are shown in Tables 3-4.

Table 3 Mixing Ratio (wt. "/1) Blaine Specific Sample Surface Arc No. (linker Anhydritc Additives Of Cement (cmlg) 1 80.0 15.0 Calcium carbonate 5.0 5520 2 80.6 15,0 Lime stone 4.4 5410 3 8016 14.0 Lime stone 4.4 5590 Anhydrous sodium 10 sulfate 81.0 15.0 Calcium carbonate 4.0 5470 Table 4-1 'l'cst Temperature 5C Test Temn e r a tgfll S ettmg (ornorcssive Strength Setting Compressive Strength imc Mortar (kg/e Time of Mortar (kg/cm") Initial lnitial- 2 3 6 3 8 S: ll'inal 2 3 6 l 28 Final (min) hrs hrs hrs day days (min) hrs hrs hrs day days days I (0-71 35 77 144 240 309 432 35-44 42 I12 I64 240 321 442 2 59-6) 34 X0 152 258 325 455 31-39 49 110 177 248 335 439 3 58-75 39 X9 153 260 330 561 32-39 51 112 I86 259 339 462 4 60-72 30 7] M9 307 437 33-42 42 109 I66 255 330 458 Table 4-2 Test Temperature 20C Test Temperature C Setting Time v Compressive Strength Setting Time Compressive Strength 5 I initial-final of Moog; t sls -l initial-final of Mortar (kg/cm") amp 6 T Flov (min) 2 hrs 3 hrs I day 3 days 28 days (min) 2 hrs 3 hrs 1 day 3 days 28 days Note: For the test temperature of 20C. citric acid in the amount of 0.1% by weight of cement was added to all the samples as retarder,

anhydrite into liquid phase at low temperatures becomes extremely faster than that of clinker and slows down hydration.

Experimental results are explained hereunder on relation between fineness of cement prepared by this invention and a setting time and compressive strength. Chemical and mineral composition of clinker and chemical composition of gypsum both used in the experiments are as shown in Tables 5 and 6.

Table 5 Chemical Composition (wt.

Mineral Composition (wt.

sio, A1103 mo, CaO so F Total c a cat C s the cement prepared by adding lime and anhydrous Table 6 dium sulfate ground separately as shown in sample No. 12 of Tables l ig. 1055a sio,+R,o., CaO so Total The reason why the cement of thts tnventton develops an excellent early strength at low temperatures and 50 3L8 later stage strength increases remarkably is supposed to be the followings. When clinker is mixed with additives consisting of carbonate or carbonate and sulfate and interground, not only particle distribution of ground clinker particles is adjusted within a narrow range by the presence of additives and clinker particle and additives are mixed homogeneously in the ground material. As a result, when hydration test is executed on the cement prepared by mixing to the above ground material powdered anhydrite, velocity of dissolution of clinker into liquid phase increases even at low temperatures as at room temperature, making the velocity of dissolution into liquid phase of clinker and anhydrite adequate to produce hydration minerals, calcium sulfoaluminate for example, and the hydration is speeded.

ln sample Nos. 9-10 in Tables l-2, mixture of clinker and anhydrite or clinker, lime and anhydrous sodium sulfate is ground, however. as anhydrite is overground selectively in this case, wheghydratipn is tested on the cement thus prepared, it is supposed that velocity of The anhydrite used in this test is prepared by burning gypsum of chemical composition as in Table 6 at the temperature of 950C in an electric furnace for 1 hour and is 8,000 cm lg (Blaine) The test was performed on cement prepared by intergrinding the said clinker, line (purity 98 percent) and anhydrous sodium sulfate in the proportion of 94:51] by weight into various fineness and then adding the said powdered anhydrite to the resulting mixture in such amount as Al O /SO weight ratio in cement thus produced is 1.0 and a compressive strength of mortar at temperature of 10C was measured (according to J 18 R 5201 testing method, which is also applied to the compressive strength tests hereunder) and setting time of mortar (cementzstandard sand=l :2, water/cement ratio 0.55, the determination of initial and final setting of cement is based on JlS R 5201 testing method forpaste setting, which is applied for the tests hereunder).

FIGS. 1 and 2 showed that at the mixing temperature of C, above 5,000 cm /g (Blaine) gave suddenly clinker also becomes large, velocity of dissolution of clinker comes to balance with that of anhydrite so as to be adequate to produce hydration minerals and thus early and later strength develop satisfactorilyv This invention relates to a process for manufacturing a rapid hardening portland cement from clinker comprising a calcium halo-aluminate having the formula C A 'CaX and at least one selected from the group consisting of C 5, C S and C AF, which comprises adding an additive consisting of at least one carbonate of calcium, sodium, potassium and magnesium, or a mixture of said carbonate and at least one sulfate of sodium, potassium, aluminium, and then adding finely powdered anhydrite to the ground mixture in an amount such that the weight ratio of Al O /SO in ce ment thus prepared is 0.6-1.8.

This invention is applied to the clinker containing 5-60 percent of C A 'CaX and the fineness of the interground mixture of clinker and additives is suitably in the range of 2,5008,500 cm /g (Blaine), preferably- 4,000-6,500 cm /g (Blaine). It is preferable to use anyhydrite prepared by burning gypsum at around,

950C and its fineness is suitably in the range of 2,500-l5,000 cm lg (Blaine), preferably in the range of 5,000-10,000 cm /g (Blaine) and it is also preferable, in the event the fineness of interground clinker and additives is low, to mix anhydrite of low fineness and Chemical Composition (wt. 7:)

it is further preferable the lower the temperature at which cement hardens, the finer the cement is. For example, when cement is prepared by mixing clinker, lime and anhydrous sodium sulfate in the weight proportion of 95:4:1, intergrinding and then adding anhydrite prepared by burning by-product gypsum prepared from wet-process phosphoric acid at 950C, anhydrite of 8,000 cm /g (Blaine) is to be added when the fineness of the ground mixture is 5,000 cm /g, and above 8,000 cm /g (Blaine) anhydrite when the ground mixture is above 5,000 cm /g (Blaine).

In this invention, the amount of carbonate of calcium, potassium and/or magnesium, etc. to be added to clinker is in the range of ll 5 percent by weight to clinker and that of sulfate of sodium, potassium, aluminium and/or magnesium is 0.1-7 percent by weight based on $0 Additives below the lower limit of the above figure has no effect and that above the upper limit is not preferable because the strength of cement is decreased.

rep,

Within the range of the above figure, the set strength increases as the amount of additives is increased but it is preferable to adjust the amount of additives according to C,,A -CaX content in clinker.

On carrying out this invention. anhydrite powder may be incorporated to the ground clinker in either of the following ways. In one method, anhydrite is separately ground to a certain fineness and mixed with the powder of mixture of clinker and a carbonate or clinker, a carbonate and a sulfate interground to the certain fineness in a mill. ln another method, round grains of anhydrite is added to a mill before the mixture powder of clinker and a carbonate or clinker, a carbonate and a sulfate is ground to a certain fineness so that the interground clinker mixture and anhydrite reaches to a desired fineness at mill outlet.

It is also possible to hasten grinding by using the same grinding aid as is used in grinding conventional portland cement clinker.

It is further possible to produce cement which hardens at low temperatures by intergrinding a mixture of conventional portland cement clinker and the clinker used in this invention and then mixing anhydrite thereto.

According to this invention, controlled setting time and high early strength development which has been unattainable hitherto can be obtained through a wide range of temperature from low to high (using at high temperatures, retarder such as citric acid should be added) and strength in later stage is greatly improved and mortar and concrete with excellent workability can be manufactured from the cement.

EXAMPLE 1 Mixture of red boxite, clay, quick lime, fluorite and a small amount of gypsum were ground, mixed and shaped under pressure and burnt at the temperature of 1,260-l ,350C so as to make a clinker which chemical and mineral composition are as shown in Table 7.

Table 7 Mineral Composition (wt.

CaO F Total C,,A-,-CaF C S Anhydrite was prepared by burning by-product gypsum prepared from wet-process phosphoric acid at 920C in a rotary kiln and then ground to a fineness of 8,230

,cm /g Blaine specifice surface area. The chemical composition of by-product gypsum is shown in Table 8.

Various cements were prepared by mixing to the clinker dolomite, lime and lime and anhydrous sodium sulfate in the proportion as shown in Table 9, grinding the resulting mixture to the fineness as shown in Table 9 in an open circuit three chamber mill of 2m in diameter and 14m in length and then mixing gypsum anhydrite prepared as described above in the proportion as shown in Table 9. Setting time and compressive strength of mortar at various temperatures were measured on the cement produced as above and results are shown in Table 9. For comparison, Table 9 includes a position as Table l l and magnesium carbonate or lime and anhydrous sodium sulfate were mixed, ground in the same mill as used in Example 1 to the fineness as shown in Table 12 and added to the resulting mixture test result on a cement prepared by the method shown 5 with anhydrite prepared from gypsum of the same comin Table 1, No. 3-4.

position as in Table 8 in the proportion as shown in TABLE J Mixing ratio of cement (wt. percent) Blaine Compressive strength of mortar specific Setting (kg/cm. Anhydrite surface Setting time of Interground materials added after area of tempermortar, Methgrinding interground ature of initial- 2 3 6 1 3 28 No. ocl Clinker Additives clinker materials mortar final hrs. hrs. hrs. day days da 5 5 60-71 38 71 13g 22g 306 44g 10 37-44 -10 103 1 .24 328 45 l 8 Dolomtte.4.4 5,130 20 3341 7 21 188 221 304 465 30 24-29 81 131 195 222 368 471 56-67 40 80 161 331 47 10 30-39 51 118 171 341 480 2...... 80.6 L1mestone,4.4 5,070 2340 89 121 108 23 3x2 488 30 25-30 90 133 201 242 2 490 5 63-7; 37 90 160 2:31 335 468 10 3 4 49 110 188 2 338 460 3 (2 80.6 ik ggj gf g g g} 14 20 26-32 00 128 102 244 320 471 30 23-30 03 141 200 238 390 497 5 30 9) 281 10 5 2 4 1 4 n 5 .0 0 20 $33 33 1,51 3 30 26-38 71 110 220 312 412 1 Method 01 this invention. 2 Method shown in Table l, N o. 8-4.

Norm-For test temperature of 20 and 30 C. in Nos. 1-3, 0.75% and EXAMPLE 2 Cement clinker of the composition as shown in Table 10 prepared by using the same materials as in Example Table 10 Chemical Composition (wt.7')

1.5% of citric acid was added respectively as retarder melted in mixing water. For 20 and 30 C. in No. 4, citric acid in the amount of 1.0% and 2.0% o! cement was added respectively as retarder.

Mineral Composition (wt. 71)

SiO A1 0; Fe O C F Total C,,A,CaF- C S Table l l f C I 1, rapid hardenmg portland cement cllnker 0f the com- TABLE 12 Mixing ratio (wt. percent) Setting lnterground Matenals ESEEE i time of Compressive strength of mortar lnter- Settmg mortar (kg/cm 3 Rapid Clinker ground temperinitialhardening containin Additive Anltymaterial ature of final 2 3 6 l 3 28 inker CnArCa 1 dnte cmJ/g. mortar (min.) hrs. hrs. hrs. day days days (Blaine) 5 75-93 14 4B 82 230 462 10 42-5 20 51 95 21 470 1...... 39. 6 40.0 Magnesium carbonate, 4.4 16 5,210 20 M 44 85 142 225 331 472 30 20-28 48 86 254 345 475 L t 4 4 1.3 77-95 g 44 $293 3:2 43(2) lrnes one. 45-55 78 1 1 -4 5 4 6 O {Anhydrous sodium sulfate, 1.0-

Nora: For test temperature of 30 C., 0.5% of citric acid was added to cement as retarder.

What is claimed: 1. A process for manufacturing a modified portland cement which rapidly hardens at low temperatures, which comprises:

mixing at least one carbonate selected from the group consisting of calcium carbonate, sodium carbonate, potassium carbonate and magnesium carbonate with a clinker which mainly consists of a calcium halo-aluminate having the formula: 1 lCaO'7Al O 'CaX in which X is a halogen and at least one mineral selected from the group consisting of 3CaO-SiO 2CaO-SiO and 4CaOAl O z ai intergrinding the mixture; and then mixing finely powdered anhydrite with the ground mixture to manufacture cement in an amount such that the weight ratio of A1 50;; in the cement is 0.6 1.8.

2. A process claimed in claim 1, wherein the clinker comprises 5-60 percent by weight of llCaO-7Al O CaX 3. A process claimed in claim 1, wherein the fineness of the interground mixture of the clinker and the carbonate is 2,500-8,500 cm /g Blaine specific surface area.

of anhydrite powder is 2,500l5,000 cm/g Blaine specific surface area.

7. A process claimed in claim 6, wherein the fineness of anhydrite powder is 5,000-10,000 cm /g Blaine specific surface area.

8. A process claimed in claim 1, wherein the fineness of anhydrite powder mixed with the interground mixture is lowered as the fineness of the interground mixture is decreased.

9. A process claimed in claim 1, wherein X is fluorme.

10. A process claimed in claim 1, wherein at least one sulfate selected from the group consisting of sodium sulfate, potassium sulfate, aluminium sulfate and magnesium sulfate is mixed besides the carbonate.

11. A process claimed in claim 10, wherein the clinker comprises 5-60 percent by weight of l lCaO-7Al- O 'CaX 12. A process claimed in claim 10, wherein the sulfate is mixed with the clinker in the amount of O. l7.0 percent.

13. A process claimed in claim 10, wherein the fineness of anhydrite is 2,500-1 5,000 cm g Blaine specific surface area.

14. A process claimed in claim 10, wherein the fineness of anhydrite added to the interground mixture is lowered as the fineness of the interground mixture is decreased.

15. A process claimed in claim 10, wherein X is fluorme. 

2. A process claimed in claim 1, wherein the clinker comprises 5-60 percent by weight of 11CaO.7Al2O3.CaX2.
 3. A process claimed in claim 1, wherein the fineness of the interground mixture of the clinker and the carbonate is 2,500-8, 500 cm2/g Blaine specific surface area.
 4. A process claimed in claim 3, wherein the fineness of the interground mixture is 4,000-6,500 cm2/g Blaine specific surface area.
 5. A process claimed in claim 1, wherein the carbonate is mixed with the clinker in the amount of 1-15 percent.
 6. A process claimed in claim 1, wherein the fiNeness of anhydrite powder is 2,500-15,000 cm/g Blaine specific surface area.
 7. A process claimed in claim 6, wherein the fineness of anhydrite powder is 5,000-10,000 cm2/g Blaine specific surface area.
 8. A process claimed in claim 1, wherein the fineness of anhydrite powder mixed with the interground mixture is lowered as the fineness of the interground mixture is decreased.
 9. A process claimed in claim 1, wherein X is fluorine.
 10. A process claimed in claim 1, wherein at least one sulfate selected from the group consisting of sodium sulfate, potassium sulfate, aluminium sulfate and magnesium sulfate is mixed besides the carbonate.
 11. A process claimed in claim 10, wherein the clinker comprises 5-60 percent by weight of 11CaO.7Al2O3.CaX2.
 12. A process claimed in claim 10, wherein the sulfate is mixed with the clinker in the amount of 0.1-7.0 percent.
 13. A process claimed in claim 10, wherein the fineness of anhydrite is 2,500-15,000 cm2/g Blaine specific surface area.
 14. A process claimed in claim 10, wherein the fineness of anhydrite added to the interground mixture is lowered as the fineness of the interground mixture is decreased.
 15. A process claimed in claim 10, wherein X is fluorine. 